The presence of toxic, mutagenic and carcinogenic contaminants in the home and work place poses serious health risks to individuals exposed to these hazardous substances. For example, hazardous airborne particles may enter the home as a result of numerous industrial and municipal processes, automotive exhaust emissions or through consumer products, as shown in Table 1.
TABLE 1 __________________________________________________________________________ Hazardous Substances Found in the Home Hazardous Toxicity Chemical Abstracts Substance.sup.a Data.sup.b Symptoms Source Reference __________________________________________________________________________ Antimony unk.-man LDL.sub.o Eczematous eruption of Outdoor aerosol 101:96795r 15 mg/kg skin, gastrointestinal infiltration, industrial upset, fatigue, source dizziness, neuralgic, pain Arsenic orl-man LD.sub.50 Liver damage, Outdoor aerosol 104:115152i 1430 .mu.g/kg disturbances of blood, infiltration and (arsenic trioxide) kidneys, nervous system. household products. Carcinogen of skin, lungs, liver. Barium orl-hmm LDL.sub.o Abdominal pain, rapid Residential coal 99:110028s 11.4 mg/kg pulse, paralysis, furnace cyanosis, death (Barium oxide) Cadmium inhl-man TCL.sub.o Lung changes, severe Household dust from 100:56164g 40 .mu.g/m.sup.3 dyspnea, prostration, mining activities death, teratogenicity Chromium scu-dog LDL.sub.o Lesions, ulcers, Portable space heaters 100:11936u 330 mg/kg carcinogen of lungs sinuses, stomach, larynx Copper orl-hmn TDL.sub.o Dizziness, convulsions, Household wood 105:213511r 120 .mu.g/kg shock, coma, death burning appliances Lead halides dnd-mam:lym Alimentary, Automotive exhaust 95;48217q 100 .mu. mol/l neuromotor, encephalic disorders, stupor, coma, death White lead orl-man: TDL.sub.o Same as lead halides Paint chips/dust 92:192400z 214 mg/kg Mercury inhl-wmm TCL.sub.o Tremors, vomiting, Cosmetics, medicines, 97:139840u 150 .mu.g/m.sup.3 kidney damage, death dental materials, toys __________________________________________________________________________ .sup.a These substances may be present as the oxide, halide or sulfate. .sup.b Sax, N. Irving, Dangerous Properties of Industrial Materials, 6th Ed., Van Nostrand Reinhold Co., New York, (1984)
Exemplary contaminants in past and present technologies, and processes that have resulted in occupational exposures and health risks to workers in numerous settings and industries, are provided in Table 2.
TABLE 2 ______________________________________ Environments in Which Health-Risk Exposure Has Occurred to Workers Chemical Hazardous Setting in Which Hazardous Abstracts Substance Substance Exposure Occurred Reference ______________________________________ Antimony and Rubber factory workers 96:222555f its compounds Nonferrous smelter workers 102:11628m Battery plant workers 95:137722t Fungicide manufacturing 88:78303n Arsenic and Copper smelter workers 98:131587t its compounds Glass manufacturing 101:78144y Wood preservative workers 97:149876a Plywood industry 104:229746m Welding 105:101994u Barium and Ceramic manufacturing 105:213582q its compounds Coal and copper slag reuse 96:167867g Phosphate processing operations 92:63916y Lead smelting plant 87:140424n Cadmium and Jewelry industry 100:73313y its compounds Pigment manufacturing 102:83616d Coal conversion facility 101:176730f Fabricating radiotherapy 105:213573n shielding blocks Phosphate fertilizer workers 99:217839j Chromium and Cement workers 100:108504q its compounds Chromium plating 101:42835k Leather industry 97:149685n Automotive paints 100:197099b Manufacturing beet sugar 101:156866b Copper and Color television manufacturing 98:59188u its compounds Jewelry casting workers 105:119945p Synthetic corundum manufactur- 96:11021r ing Brass foundry 104:229747n Gun metal foundry workers 105:11328a Lead and Toll-booth workers 99:93042x its compounds Steel workers 97:60227s Solder finishing 99:199847d Newspaper workers 96:167854a Plastics industry 96:222534y Mercury and Dental clinic workers 97:43520q its compounds Thermometer manufacturing 101:136219q Chloralkali industry workers 98:95002n Synthetic fuel manufacturing 96:186507f ______________________________________
Nuclear medicines also can pose a threat to health care professionals and patients. Spills and other contamination involving such compounds make preparation rooms and administration areas increasingly more hazardous. A common radiopharmaceutical is technetium 99m which is the decay product of molybdenum-99. Technetium 99m is combined with other agents to yield a series of radiopharmaceuticals such as Technetium Tc-99m albumin colloid, Technetium Tc-99m disofenin, Technetium Tc-99m diphosphonate, Technetium Tc-99m mebrofenin, Technetium Tc-99m medronate, Technetium Tc-99m gluceptate, Technetium Tc-99m lidofenin, Technetium Tc-99m succimer, Technetium Tc-99m sulfur collid, Technetium Tc-99m polyphosphate, Technetium Tc-99m pyrophosphate. Other radiopharmaceuticals include iodinated I-125 albumin, I-131 iodocholesterol, I-131 hippuran, I-131 orthoiodohippurate, Cr-51 sodium chromate, Se-75 selenomethionine, P-32 sodium phosphate, and In-111 chloride.
Organic spills are another source of hazardous materials. Spills of pharmaceuticals, particularly radiopharmaceuticals, PCB's, formaldehyde, agricultural chemicals, chlorinated hydrocarbons, e.g. 1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-endo-exo-1,4:5,8-dimethan onaphthalene (Aldrin), octachlorotetrahydromethanoindan(Chlordane), 1-chloronaphthalene, 1-chloro-2-nitrobenzene, chlorophenol, o,o-dimethyl-o-(3-chloro-4-nitrophenyl)thiophosphate(Chlorthion) 2,4-dichlorophenoxyacetic acid(2,4-D), dichlorodiphenyltrichloroethane(DDT), alpha, alpha-dichlorovinyldimethyl phosphate (DDVP), 3,4-dichloroaniline, 1,3-dichloro-5,5-dimethylhydantoin (DDH), 2,4-dichlorophenol, 1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a -octahydro-endo,1,4:5,8-dimethanonaphthalene (Dieldrin), 1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene (Heptachlor), 1,1,1-trichloro-2,2-bis-(p-methoxyphenyl)ethane (Methoxychlor), chlorinated dibenzo dioxins, 1-chlorodibenzo-p-dioxin, 1,2,4-trichlorodibenzo-p-dioxin, chlorinated diphenyls (PCBs), trichlorobiphenyl, tetrachlorobiphenyl, pentachlorobiphenyl, hexachlorobiphenyl, and other hazardous organic chemicals can pose a serious threat to individuals and to the environment.
Lead is of particular concern because of its prevalence and serious health consequences. The major sources of lead in the environment include drinking water contaminated with lead from pipes and solder, food containing lead from contaminated soils, emissions from gasoline combustion, and lead paint. Lead is very toxic, and is particularly damaging to the neurological development of young children. High levels of lead in the body can cause convulsions, mental retardation and death. Even low levels can lead to reduced intelligence, poor short-term memory, and poor hand-eye coordination. Lead poisoning is one of the United States' most widespread childhood health problems. U.S. Department of Housing and Urban Development Report to Congress: Comprehensive and Workable Plan for the Abatement of Lead-Based Paint in Privately Owned Housing (1990).
Lead-based paint in housing is a major source of lead in children. The hazard arises from loose lead paint on the interior or exterior of their housing, as well as in interior and exterior dust from lead paint. A significant source of this hazardous dust is the poor abatement procedure of scraping, sanding and heat treating the paint surfaces. These unsafe methods may increase the risk of lead poisoning by creating air-borne and surface dust which is heavily contaminated with lead.
Most interior lead dust is found in and around the windows, in the window wells and on sills. This may be due to exposure to exterior dust, to the dust caused by the abrasive action of opening and closing the windows, and to less frequent cleaning of window wells and sills. Windows contain many channels, corners, and uneven surfaces which are difficult to gain access to, and which make these surfaces difficult to clean.
Traditional abatement methods used to remove lead and other hazardous substances from home and work environments commonly involve either wet wiping with cleaning solutions and absorbants or using vacuums, e.g., high efficiency particle accumulators (HEPA vacs). Yet, studies evaluating the effectiveness of these methods have shown that the level of cleanliness needed to prevent health risk may not be afforded by either technique.
Wet wiping is typically carried out by applying a cleaning solution to the contaminated area, scrubbing to achieve dislodgement and suspension, and absorbing both the lifted contamination and cleaning solution with an absorbant material.
Some of the major shortcomings of wiping include the application of low viscosity, highly penetrating solutions which can cause surface contamination to percolate deeper into subsurface regions, thereby escaping removal. This also can spread contamination over wider areas and into regions that were not previously contaminated. Furthermore, interactions between surfaces and contaminants vary considerably, and generic cleaners may not provide the wetting, solubilization, emulsification and suspension properties needed to dislodge the contaminant from its resting position and transfer it to the solution for subsequent absorption and removal.
Effective wiping may not be achieved in areas that are geometrically complex (window well corners and channels), physically obstructed (under equipment), or located in inaccessible surface regions such as cinder block pores. Additionally, wiping provides no means of protecting workers from exposure, and protective suits with external air supplies, which are burdensome and restrictive to detailed abatement functions, are often used.
With conventional wet wiping the degree to which cleanliness is achieved is unknown, and the level of residual contamination requires subsequent analysis, usually by a skilled technician with sophisticated and costly equipment.
Like wet wiping, wet/dry vacuuming abatement also possesses shortcomings that can hinder achieving the requisite degree of cleanliness. Wet vacuum processes also use thin, low viscosity, highly penetrating solutions that can carry surface contamination deeper into porous, open structures. Without a visual means of tracking where the vacuum head has passed, areas and sections may be overlooked and remain unvacuumed. In dry vacuuming, beater brush action may actually exacerbate the problem by forcing contamination deeper into porous surfaces or spreading the contamination to new areas.
Cumbersome vacuum head designs, especially present with wet vacuuming, may prevent sufficient contact in geometrically complex, obstructed or constricted areas. Contamination compressed into open surfaces (wood and cement) may be sufficiently restrained to resist removal by the force of vacuum only, and may emerge later due to common processes involving impact, abrasion, shear and adhesion.
Wet/dry vacuuming offers no protection to the workers who usually must don protective clothing. The degree of cleanliness achieved by vacuuming is also unknown and requires analysis by a separate procedure.
The failure of conventional cleaning methods to correctly meet the needs found in hazardous substance abatement has resulted in serious increases in health risk, permanent loss of health and loss of life; the expensive removal and replacement of built-in structures such as window and door frames, flooring, counter and bench tops; and even the entombment or condemnation of useful facilities (research labs and "hot" rooms). Thus, there is a great need for an abatement process which can remove lead and other contaminants from a surface or spill safely, thoroughly, and quickly.
There is also a need for an inexpensive and reliable method for detecting lead and other contaminants on site. A detection system that is useful for measuring initial contamination levels, assessing the effectiveness of an abatement procedure, and periodically testing the area to ensure that it remains free of the contaminant is essential to a thorough abatement strategy. Current technologies require skilled technicians and expensive instruments, and may not yield accurate results.
There also is a need for methods of mitigating the toxicity of a contaminant prior to or during the abatement process in order to decrease the hazard to abatement workers.